It is generally recognized that railroad flatbed cars are efficient and economical means for transporting heavy loads at high speeds and with a high degree of safety. Such loads often are in the form of wheeled vehicles, particularly automobiles, which are required to be tied down to the flatbed surface during transport. Of all of the requirements for tying down automobiles for transport it is most important to provide devices which not only maintain a fixed position of the automobile relative to the flatbed car but also maintains that position during sudden or quick accelerations or stops or even upon relatively minor impacts of the main carrier vehicle.
Transporting automobiles or other wheeled vehicles on railroad flatbed trucks or seagoing vessels in the past has normally been directed to restraining the actual body of the automobile by chains and devices which restrain the body from movement in several directions. Often these devices include a four point chain system emanating from a position centrally located with respect to the automobile and extending in different directions toward the four corners of the frame. Thereafter, one or more ratcheting devices are actuated to place the chains in tension so as to restrain the automobile from movements during transit.
These prior art devices have been known to suffer from several diverse deficiencies. For example, they provide relatively extensive interference to the movement of the automobiles on the flatbed. In some instances where an automobile has a relatively low chasis it has been found that the bulk and interference of the chains and related tensioning equipment actually interfere with the frame of the automobiles thereby preventing them from movements into and out of position on the flatbed.
One prior art system includes hold-down devices for automobiles which surround a major portion of the individual automobile wheels and are each provided with a tensioning mechanism to secure the wheel against the base support. Another system provides individual wheel hold-down harnesses and wheel chocks positioned on each side of the wheel and provided with a crank and associated hardware mechanism for applying tension to the harness while jamming the chocks against the wheel. Still another system includes a multiple chain and ratchet system to secure the frame of the vehicle to the flatbed with the ratchet system maintaining the tension thus applied to the chains. In general, there are numerous systems for tying down or otherwise securing automobiles or other wheeled vehicles to flatbed transport cars. These systems often include common hook-type and chain hardware, cranks, ratchet wheels or the like. However, although many of these systems are usually only effective in applying tension to chains or harnesses which hold down selected components of the automobile, none of them are capable of maintaining the tension thus applied or even taking-up slack in the tie-down devices caused by minor aberrations or changes generally occurring in the tension system during transport. For example, on occasion the main transport vehicle in a minor accident will undergo impact with another automobile causing shifting of the transport vehicles with resultant stretching of components or distortion of tires at critical locations. When such incidents occurred with prior art systems, these systems do not have the capability of automatically replacing the resultant lost tension on the major tie-down components to thereby take-up the slack created during the disturbances. Accordingly, when a disturbance does occur, resumption of motion of the flatbed is normally prevented by the fact that some or most of the vehicles previously tied down have worked themselves loose. Further, these prior art devices do not include features to transfer the main tension carrying load within a chain or other tie-down component so as to shift that tension load to a major load carrying portion of the flatbed vehicle while protecting the main tensioning mechanism from fluctuations in tension caused by impact of the main vehicle or quick accelerations or decelerations thereof. I have invented an apparatus and system for tying down wheeled vehicles which avoids all of the aforementioned disadvantages of the prior art devices.